A COAL mine explosion and a fire in western Turkey that has so far killed more than 200 people is likely to be the country's deadliest mining disaster ever, Energy Minister Taner Yildiz said on Wednesday.

Yildiz said the death toll in the mine in the town of Soma, around 120 km (75 miles) northeast of the Aegean coastal city of Izmir, rose to 205. Hundreds were still believed to be trapped underground, but he declined to provide the exact figures.

Prime Minister Tayyip Erdogan declared three days of national mourning.

The disaster highlighted Turkey's poor record on worker safety and drew renewed opposition calls for an inquiry into a drop in safety standards at previously state-run mines.

The International Labour Organization ranked the EU candidate nation third worst in the world for worker deaths in 2012.

Yildiz said the fire was still burning underground, which miners said was hampering the rescue operation and denting hopes of finding more survivors. A pall of smoke hung above the area.

The blast happened during a shift change, leading to uncertainty over the exact numbers of miners trapped inside.

Yildiz earlier said 787 workers were in the mine at the time and that the death toll may rise further.

"I have to say that our hopes are dimming in terms of the rescue efforts," he said.

Rescue workers pumped oxygen into the mine to try to keep those trapped by the blaze alive, as thousands of family members and co-workers gathered outside the town's hospital. Many of the dead had suffered carbon monoxide poisoning, Yildiz said.

Some 93 people were rescued, including several rescuers, and 85 of them were being treated for their injuries, the Disaster and Emergency Management Presidency said in an email.

One relative told broadcaster CNN Turk that his 15-year-old nephew was among workers still trapped inside the shaft.